Cause : Main contactor acknowledge missing comes when a communication issue between the drive and the main contactor. The main contactor is a switch that controls the power supply to the drive. If the drive cannot confirm that the main contactor has received and executed its command, it will generate this fault.

F524 Main contactor acknowledge fault in ABB DCS800 drive indicates that the drive is unable to confirm that the main contactor has successfully closed.

1. Visually inspect the main contactor for any signs of damage, such as burned contacts or loose connections.
2. Inspect the wiring between the drive and the main contactor for any signs of damage, loose connections, or corrosion.
3. Test the drive with a different main contactor to isolate the issue.
4. If necessary, replace the main contactor with a new one.